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Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B34 engine coolant temperature sensor.
  2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.Test for less than 5 Ω between the low reference circuit terminal A and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  3. Ignition ON, verify the scan tool ECT Sensor parameter is less than -40°C (-40°F).
    • If warmer than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the K20 engine control module.
  4. Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 149°C (300°F).
    • If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  5. If all circuits test normal, test or replace the B34 engine coolant temperature sensor.
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